1. Technical Field of the Invention
The invention relates to a neck end for a filling neck of a container, in particular a tank of a motor vehicle, with a pipe piece and a closure mechanism which has an upper pivoting flap arranged in the pipe piece and a lower sealing flap arranged thereunder, wherein the upper pivoting flap and the lower sealing flap are articulated about an articulation point on one side of the pipe neck, and in each case the upper pivoting flap can be opened with its end opposite the articulation point along a first circular segment path as a result of a pivoting movement about the articulation point by the pressure of an introduced filling pipe, and the lower sealing flap can be opened along a second circular segment path as a result of a pivoting movement about the articulation point.
Such neck ends are mostly used without an additional cap behind a pivoting flap for closing a fuel tank of a motor vehicle. The invention is however not limited to this use, but relates to all neck ends for other fillable containers which can be closed automatically by means of a double flap even if they have an additional cap or are permanently connected to a neck pipe. Such containers can for example be oil tanks for the engine oil of motor vehicles or else water tanks of ships etc.
2. Description of Related Art
Neck ends which can be closed without needing a cap are known from DE 203 09 799.8 U. In the neck end described in the cited document, the neck is closed by means of two flaps which are arranged one above the other in the neck and are held against a sealing face by the force of one closure spring each. When the output pipe of a pump nozzle or a spout of a storage canister is inserted, the two flaps are pressed downwards, producing a continuous opening.
Although this closure provides good sealing even without an additional tank cap, it would be desirable if it could be further improved and additionally had a means for preventing incorrect filling. In particular in the case of modern engines, it is increasingly important to ensure the correct type of fuel, as for example modern injection systems in common rail diesel injection are lubricated by the lubricant content of the diesel fuel and can suffer severe damage even after a short operating time with petrol.
EP 1319545 A describes such a method for preventing a neck from being filled with unsuitable fuel. To do this, hooks are distributed over the circumference of the neck, which hooks have a bent central region which is then pushed away by the front edge of the pump nozzle when the pump nozzle has a sufficient diameter. As a result, the hooks at least cannot all be displaced outwards if a pump nozzle which is too small is inserted, in which case the lower part of the pump nozzle engages with the end regions of the hooks which are not pushed outwards, so that the pump nozzle cannot be introduced further into the neck but snags.
Although this neck provides the possibility of preventing incorrect filling, it has the disadvantage that although the pump nozzle cannot be introduced completely into the neck, filling of the neck with at least a small amount would still be possible with corresponding disregard of the safety instructions, because no cap is blocked with the safety elements, only the pump nozzle is prevented from being inserted into the neck. This does not however prevent the filling function of the snagged, excessively small pipe of the pump nozzle from being operated, with the result that fuel of an unsuitable type then flows into the neck.
A further disadvantage of this configuration consists in that the displacement of the hooks requires a lot of mechanical effort, which results in unreliable functioning. For example, some of the hooks can be pushed away by inserting the pump nozzle in a tilted manner and with a certain amount of force, so that only some of the hooks engage which can then bend according to their function. Over time, the neck end can be damaged in this manner, in particular if the user of the vehicle tries to force the pipe of the pump nozzle in.
EP 1262355 A again discloses a capless neck end which has a means for preventing filling with the wrong fuel in its lower region. To do this, a safety element which can be displaced transversely to the neck longitudinal axis and is displaced to the side by the penetrating pipe section of the pump nozzle is provided above a lower covering flap. As a result of this displacement movement, an edge of the lower covering plate is disengaged so that a lock which is produced by this engagement between the displacement element and the lower covering flap is lifted and the pump nozzle can be inserted further, with the lower covering flap pivoting up.
This configuration firstly has the disadvantage that the pump nozzle rests directly on the lower covering flap, that is, acts on the actual closure flap of the neck. If attempts are then made to fill up with the “wrong” pump nozzle, this can cause damage to this sealing flap as a result of the pressure on the lower covering flap, which is not unlocked.
A further disadvantage of this configuration is that tilted, oblique placement of the pump nozzle can likewise cause unlocking although the diameter of the pipe of the pump nozzle is actually too small. Furthermore, the engagement of the lower covering plate in the groove of the displacement element is comparatively prone to faults, as this groove can become damaged or disengaged for example owing to dirt or wear as a result of the regularly occurring lateral sliding of the pipe in the displacement element. In this case, however, the safety function is cancelled, with the result that the lower cover can be tilted downwards even with smaller pipe diameters.
A further disadvantage of this configuration consists in that the safety means also allows the nose of an unsuitable pump nozzle to be inserted comparatively deeply before the driver can establish that the pump nozzle does not actually fit into the neck. Many users will however not realise this, but will instead think that this is normal for this configuration, that the pipe section of the pump nozzle cannot be completely sunk, or will assume that the neck is defective. This can result in this user either continuing to push with force or starting to fill up, which then in turn results in the petrol flowing into the region between the upper edge of the neck end and the lower cover and flowing from there either into the fuel supply through the legally required return line to the tank or into the reserve tank. Neither of these is desirable in practice, for understandable reasons.
WO 2006/084908 describes a neck end with two pivoting flaps as a capless closure, in this case the upper pivoting flap being configured to prevent filling with unsuitable fuel and the actual seal of the tank being formed by the lower pivoting flap.
Although this solution provides reliable sealing and sufficient protection from incorrect filling, it has the disadvantage, as in the other, above-described solutions, that the thickened end region of the pipe neck which must receive the capless mechanism must be relatively long to be able to accommodate the mechanical functional elements. This in turn results in a larger space requirement for the pipe neck, which is not always available, depending on the vehicle design and in particular with subsequent conversion from a conventional to a capless neck with an otherwise unchanged vehicle design.
A further disadvantage of the prior art is the fact that the capless necks are not sufficiently secure from the introduction of a drainage hose with the intention of theft. This is mostly solved by means of external covering flaps, the lock of which can also usually be levered off comparatively easily.